Hatchback EX Center-mounted Exhaust lowered my MPG

Zuko

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I recently bought the 2020 Sport Diffuser and rerouted my exhaust to center mount. Ever since then my MPG has only hit 25.5-25.6 while it use to easily hit 30. My mufflers are still there and the only thing the muffler shop did was add a right angle pipe for it to sit in the middle. I don't know the mechanics behind the exahust flow but is the reason it gone down to 25 mpg is because the air needs more time to escape with the extra pipings?
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bluehatch17

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How long have you driven it? Mileage and time wise. Mpg is a very fickle thing dependent on a wide ranging variety of variables.
 

Bluefire64

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Any more spirited driving than usual? That’s why mine went down.
 
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Zuko

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How long have you driven it? Mileage and time wise. Mpg is a very fickle thing dependent on a wide ranging variety of variables.
I have a 2018 EX w it just hitting 28k miles.
 
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Zuko

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Any more spirited driving than usual? That’s why mine went down.
haha possibly, will continue to monitor. I do know my AC has been running everytime im in the car. Maybe that is a reason as well?
 


bluehatch17

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If you’ve driven a few hundred miles and 2/3 weeks. That’s not enough to make a determination on exact cause/effect. If it has been thousands of miles and few months. Then, yeah, the exhaust might have caused something.
 

Bluefire64

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haha possibly, will continue to monitor. I do know my AC has been running everytime im in the car. Maybe that is a reason as well?
AC will put a load on MPG definitely. I remember back in the day sweating in my Integra just to get every last MPG.
 
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Zuko

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AC will put a load on MPG definitely. I remember back in the day sweating in my Integra just to get every last MPG.
Ill test it out without AC since the weather in CA has been going down. But since the quarantine, I don't really drive that often either.
 
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Zuko

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If you’ve driven a few hundred miles and 2/3 weeks. That’s not enough to make a determination on exact cause/effect. If it has been thousands of miles and few months. Then, yeah, the exhaust might have caused something.
Thanks, Ill continue to monitor it when I put in new gas.
 

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Check your tire pressure as well even if the TPMS light is not lit. You can also do a full reset by removing the negative terminal from the battery for 5-10 mins and re-attach it again, do an idle relearn for about 10 minutes at least then drive it to check what mileage you’ll get.
 

Donkeyhotay123

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AC will put a load on MPG definitely. I remember back in the day sweating in my Integra just to get every last MPG.
I guess things are serious when you need to hit the green button and turn off the AC.
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